This invention relates to a method and apparatus for recording magnetic latent images on a medium utilizing Magnetography and, particularly, to the obtaining of natural half-tones by such a method.
Magnetography is a method for forming magnetic latent images on a recording medium by a recording head, turning said latent images into visible images with the use of magnetic toners and, further, if it is necessary, printing said visible images on a printing paper to make a hard copy of pictures.
Research and development into making practicable use of Magnetography has not been successful, although Magnetography has been regarded as a potential alternative to Xerography. One of the difficulties involved in making practicable use of Magnetography resides in the fact that it is not easy to obtain a reproduced copy having half-tones, particularly natural half-tones. Possible solutions for this problem, such as a method of varying the recording current of a recording head in accordance with the tones of the picture, or of using a recording head having a V-shaped gap, have been proposed (Japanese Patent Publication Sho. 38-13730). The method of using a recording head having a V-shaped gap utilizes the characteristic of the variation of the size of a recorded dot in accordance with the intensity of the recording current. However, practically speaking, it is difficult to obtain natural half-tones or so-called actual photographic half-tones having the characteristic of continuity of tone by either the V-shaped gap method or the other proposed method mentioned above.